Magnetic head apparatus and drive apparatus including magnetic head apparatus

ABSTRACT

A narrow magnetic body  66  in which outward path and inward path recording magnetic head devices  1 WF and  1 WR, capable of recording at least data on a metal evaporated type magnetic tape  51  running in the outward and inward direction and vice versa along the longitudinal direction, comprise the operation magnetic gaps GF and GR with the asymmetric structure is located at the leading side of the metal evaporated type magnetic tape  51 . With this arrangement, magnetic field influence exerted by the narrow magnetic body can be decreased, and difference produced between magnetic recording and reproducing characteristics when the metal evaporated type magnetic tape is transported in the outward direction and in the inward direction can be decreased. Also, deteriorations of characteristics deteriorated by off-track upon reproduction can be improved. Thus, when the recording magnetic heads with the operation magnetic gaps having the asymmetric structure are in use and the metal evaporated type magnetic tape is transported in the outward and inward direction and vice versa, difference produced between magnetic recording and reproducing characteristics when the metal evaporated type magnetic tape is transported in the outward and inward direction and vice versa can be decreased. Also, deteriorations of characteristics deteriorated by off-track upon reproduction can be improved.

BACKGROUND OF THE INVENTION

1. Filed of the Invention

The present invention relates to a magnetic head apparatus using a metalevaporated type magnetic tape and a drive apparatus including a magnetichead apparatus.

2. Description of the Related Art

In recent years, in accordance with an explosive increase of a dataamount, the increase of a storage capacity becomes the most urgent needin a tape-system storage system, and hence it is requested to increase arecording density to realize the above-mentioned increase of the storagecapacity.

Under such circumstances, there is a trend that a so-called linear typemagnetic recording tape system in which a magnetic tape is transportedin the outward and inward direction and vice versa relative to amagnetic tape so as to record thereon data in a serpentine fashion iswidely used increasingly.

However, in a magnetic tape formed of a coating type magnetic layer andwhich is now commercially available on the market, the increase of therecording density seems to reach its limit, and under the presentcircumstances, it cannot be expected that recording density will not beincreased more than the present high recording density. For this reason,also in the linear type magnetic recording tape system, it has beendiscussed to use a so-called metal evaporated type magnetic tape for usein high recording density and if which magnetic layer is formed of aferromagnetic metal evaporated film.

However, in the metal evaporated magnetic tape, its recording andreproducing characteristics become different depending upon the slidingdirection in which a magnetic tape is slidably transported on a magnetictape. The reason for this is that, since the magnetic layer is formed byrhombic vapor deposition of ferromagnetic metal, the magnetic layer hasa rhombic pyramid structure to exhibit rhombic magnetic anisotropy.

So far there have been proposed metal evaporated type magnetic tapes inwhich difference between recording and reproducing characteristics inaccordance with the sliding direction, that is, polarity can be improved(for example, see cited patent references 1, 2 and 3).

In these previously proposed metal evaporated type magnetic tapes,difference between recording and reproducing characteristics relative tothe sliding direction can be improved by selecting factors of themagnetic layer, such as structure, film thickness and magneticproperties.

[Cited patent reference 1]: Official gazette of Japanese laid-openpatent application No. 4-353621

[Cited patent reference 2]: Official gazette of Japanese laid-openpatent application No. 4-353622

[Cited patent reference 3]: Official gazette of Japanese laid-openpatent application No. 5-182168

In the linear type magnetic recording tape system, in order to increasethe recording capacity more and to realize the higher recording density,it is requested to narrow the width of the recording track more.Concurrently therewith, it is requested to narrow the track width of theoperation magnetic gap of the magnetic head. From these requests, as arecording magnetic head, there is used a thin film recording head havinga microminiaturized structure that can be manufactured by a thin filmtechnology in the semiconductor manufacturing technology.

In this thin film magnetic head, at least one of upper and lowermagnetic cores comprising the operation magnetic gaps at their frontportions is composed of a thin film magnetic layer, and the frontportion comprising the operation magnetic gap of only one of themagnetic cores composed of the thin film magnetic layers is selected soas to have a narrow width having a target track width. In this manner,the magnetic core having the narrow front portion and the magnetic corehaving the wide front portion are opposed to each other to construct theoperation magnetic gap, and the track width of the operation magneticgap is determined by the narrow front portion. In the thin film magnetichead of this kind, while its operation magnetic gap has an asymmetricstructure relative to the center surface, the track width is determinedby the thin film magnetic layer processed with high accuracy and hencethe track width of the operation magnetic gap can be microminiaturizedwith high accuracy.

Since the thin film recording head is manufactured with application ofthe thin film pattern technology used in the semiconductor manufacturingprocess as described above, a recording track width is accurate and ithas less dispersions. Therefore, as compared with a conventional MIG(Metal in Gap) type magnetic head, this thin film magnetic head has anadvantage such that it is suitable for the application to high-densitytape systems such as a narrow track multi-channel linear system.

However, when data is recorded on the magnetic tape by the thin filmhead with the operation magnetic gap having the asymmetric structure asdescribed above, complex magnetic fields are generated in the edgeportion of the track width direction. Also, as mentioned hereinbefore,since the metal evaporated type magnetic tape has the rhombicanisotropy, when data is recorded on this magnetic tape, recording andreproducing characteristics of the thin film magnetic head and the metalevaporated type magnetic tape are inevitably changed so much during themagnetic tape is being transported in the outward and inward directionand vice versa.

Further, when data is recorded on the metal evaporated magnetic tape bythe thin film magnetic head with the operation magnetic gap having theasymmetric structure, a problem arises, in which an S/N (signal-to-noiseratio) is considerably lowered by off-track in which the thin filmmagnetic head is shifted from the center of the track upon reproduction.

SUMMARY OF THE INVENTION

In view of the aforesaid aspect, it is an object of the presentinvention to provide a magnetic head apparatus and a drive apparatusincluding a magnetic head apparatus in which a problem in which magneticrecording and reproducing properties become different in the outward andinward transports of a magnetic tape can be solved and deteriorations ofreproducing characteristics deteriorated when a reproducing magnetictape is shifted from the center of a recording track due to off-trackupon reproduction can be improved even when a recording magnetic headwith an operation magnetic having an asymmetric structure and a metalevaporated type magnetic tape having rhombic magnetic anisotropy are inuse.

It is another object of the present invention to provide a magnetic headapparatus and a drive apparatus including a magnetic head apparatuswhich make effective use of the fact that a magnetic recording head hasa transport direction to provide excellent frequency characteristics andthe fact that a metal evaporated type magnetic tape and a thin filmmagnetic recording head have a relative transport direction to decreasea difference between electromagnetic transduction characteristics.

According to an aspect of the present invention, there is provided amagnetic head apparatus which is comprised of a magnetic head main bodyincluding an outward path recording magnetic head device and an inwardpath recording magnetic head device for carrying out at least magneticrecording to form recording tracks on an outward path and an inward pathof the outward and inward transport of a metal evaporated type magnetictape along the longitudinal direction of the metal evaporated typemagnetic tape while the metal evaporated magnetic tape is transportedreciprocally in the longitudinal direction, wherein the recordingmagnetic head device is composed of opposing first and second magneticbodies, the opposing first and second magnetic bodies having anoperation magnetic gap formed between their front portions, theoperation magnetic gap has an asymmetric structure in which a width ofthe front portion of the second magnetic body is selected to be narrowerthan that of the front portion of the first magnetic body, a track widthof the operation magnetic gap being determined by a width of the frontportion of the magnetic body and the outward path recording magnetichead device and the inward path recording magnetic head device arelocated in such a manner that the second magnetic body having the frontportion with the narrow width is located on the leading side withrespect to the direction of the outward path and the inward path of themetal evaporated type magnetic tape.

According to other aspect of the present invention, there is provided adrive apparatus including a transport drive unit for transporting ametal evaporated type magnetic tape in the outward and inward directionand vice versa and a magnetic head apparatus including magnetic headdevices for recording and reproducing the metal evaporated type magnetictape, comprising a magnetic head apparatus, the magnetic head apparatuscomprising a magnetic head main body including an outward path recordingmagnetic head device and an inward path recording magnetic head devicefor carrying out at least magnetic recording to form recording tracks onan outward path and an inward path of the outward and inward transportof a metal evaporated type magnetic tape along the longitudinaldirection of the metal evaporated type magnetic tape while the metalevaporated magnetic tape is transported in the outward and inwarddirection and vice versa along the longitudinal direction, wherein therecording magnetic head device is composed of opposing first and secondmagnetic bodies, the opposing first and second magnetic bodies having anoperation magnetic gap formed between their front portions, theoperation magnetic gap has an asymmetric structure in which a width ofthe front portion of the second magnetic body is selected to be narrowerthan that of the front portion of the first magnetic body, a track widthof the operation magnetic gap being determined by a width of the frontportion of the magnetic body and the outward path recording magnetichead device and the inward path recording magnetic head device arelocated in such a manner that the second magnetic body having the frontportion with the narrow width is located on the leading side withrespect to the direction of the outward path and the inward path of themetal evaporated type magnetic tape.

According to a further aspect of the present invention, in theabove-mentioned drive apparatus including a magnetic head apparatus, theoutward path recording magnetic head device and the inward pathrecording magnetic head device have the second magnetic bodies made ofthin film magnetic material to form the operation magnetic gaps at theirnarrow front portions.

In accordance with yet a further aspect of the present invention, in theabove-mentioned drive apparatus including a magnetic head apparatus, themagnetic head main body has a plurality of the outward path recordingmagnetic head devices and a plurality of the inward path recordingmagnetic head devices arrayed on parallel different straight lines witha predetermined spacing, the inward path reproducing magnetic head isformed on the side adjacent to the outward path recording magnetic headdevice in the portion where the outward path recording magnetic headdevice and the inward path recording magnetic head device are arrayed,the outward path reproducing magnetic head device is formed on the sideadjacent to the inward path recording magnetic head device, the magnetichead main body is moved in the width direction of the metal evaporatedtype magnetic tape with respect to the outward path and the inward path,with respect to the outward path, the outward path recording magnetichead device-magnetically records data on a selected track and theoutward path reproducing magnetic head on the selected track reproducesrecorded data and with respect to the inward path, the inward pathrecording magnetic head device magnetically records data on otherselected track and the inward path reproducing magnetic head device onthe other selected track magnetically reproduces recorded data.

As described above, in the magnetic head apparatus and the driveapparatus according to the present invention, the recording magnetichead device capable of at least recording data includes one of the firstand second magnetic bodies comprising the operation magnetic gap, thatis, the second magnetic body having the asymmetric structure with thenarrow width. In this manner, since only one magnetic body forms theoperation magnetic gap structure with the asymmetric structure todetermine the track width, the track width of the operation magnetic gapcan be set to be narrow and accurate as mentioned before. Further, whenthe second magnetic body is composed of the thin film magnetic body, thenarrow track width can be determined with higher accuracy.

Further, according to the present invention, in the recording magnetichead device with the operation magnetic gap having this asymmetricstructure, the second magnetic body with the narrow width is located onthe leading side with respect to the direction in which the recordingmagnetic head device is transported relative to the metal evaporatedtype magnetic tape, that is, the second magnetic body is located on theentrance side in which the metal evaporated type magnetic head entersinto the recording magnetic head device. According to this arrangement,as is clear from the descriptions which will be made later on, even inthe metal evaporated type magnetic tape having the rhombic magneticanisotropy, degree between the electromagnetic transductioncharacteristics become different due to the transport direction of themetal evaporated type magnetic tape can be decreased. In addition, it ispossible to improve deteriorations of the reproduced signal deterioratedwhen the reproducing magnetic head is shifted from the center of therecording track, that is, off-track occurs.

That is, according to the present invention, the high density recordingcan be realized by the magnetic gap with the asymmetric structure. Inthis case, it can be considered that the aforementioned problemsencountered with the related art can be solved by alleviating bothinfluence of distortion of the recording magnetic field produced at theedge portion of the track width direction by the second magnetic bodywith the narrow width comprising the operation magnetic gap andinfluence of polarity of evaporated particles produced by rhombicvapor-deposition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically showing an arrangement of adrive apparatus according to an embodiment of the present invention;

FIG. 2 is a schematic diagram showing an example of a format of amagnetic tape according to the present invention;

FIG. 3 is a perspective view schematically showing an arrangement of amagnetic head apparatus according to an embodiment of the presentinvention;

FIG. 4 is a schematic front view showing a main portion of a magnetichead main body of the magnetic head apparatus according to the presentinvention;

FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 4 andshows a main portion of an example of the magnetic head main body of themagnetic head apparatus according to the present invention;

FIG. 6 is a schematic diagram showing a flat surface pattern of arecording magnetic head of the magnetic head apparatus according to thepresent invention;

FIGS. 7A and 7B are diagrams to which reference will be made inexplaining operations of recording magnetic heads according to thepresent invention and shows relationships among a type A recordingmagnetic head and the transport direction of the metal evaporated typemagnetic head and a type B recording magnetic head and the transportdirection of the metal evaporated type tape, respectively;

FIG. 8 is a diagram showing characteristic curves obtained whenfrequency characteristics of reproduced outputs from the type Arecording magnetic head and the type B recording magnetic head aremeasured;

FIG. 9 is a diagram showing characteristic curves obtained whenrecording current dependences of reproduced outputs from the type Arecording magnetic head and the type B recording magnetic head;

FIG. 10 is a diagram showing characteristic curves obtained whenfrequency characteristic curves of the reproduced outputs from the typeA recording magnetic head and the type B recording magnetic head underthe condition in which the reproduced track width is made larger thanthe recording track width;

FIG. 11 is a diagram showing characteristic curves obtained whenrecording current dependences of reproduced outputs from the type Arecording magnetic head and the type B recording magnetic head under thecondition in which the reproduced track width is made smaller than therecording track width;

FIG. 12 is a diagram showing characteristic curves obtained whenrecording current dependences of reproduced outputs from the type Arecording magnetic head and the type B recording magnetic head under thecondition in which the reproduced track width is made larger than therecording track width;

FIG. 13 is a diagram showing characteristic curves obtained whenrecording current dependences of reproduced outputs from the type Arecording magnetic head and the type B recording magnetic head aremeasured under the condition in which the reproduced track width is madesmaller than the recording track width;

FIG. 14 is a schematic diagram showing a recorded pattern obtained bythe type A recording magnetic head through a magnetic force microscope(MFM); and

FIG. 15 is a schematic diagram showing a recorded pattern obtained bythe type B recording magnetic head through the magnetic force microscope(MFM).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A magnetic head apparatus and a drive apparatus including a magnetichead apparatus according to embodiments of the present invention will bedescribed below.

FIG. 1 is a perspective view schematically showing an arrangement of adrive, apparatus according to the present invention, for example, thecase in which the present invention is applied to a linear tape driveapparatus for use with a data storage system of a computer system.

A linear tape drive apparatus, generally depicted by reference numeral50 in FIG. 1 according to the present invention, includes a magnetichead apparatus 60 according to the present invention and a transportdrive portion 70 to transport a metal evaporated type magnetic tape 51in front of the magnetic head apparatus 60 in the outward and inwarddirection and vice versa.

This transport drive portion 70 includes a tape cassette loading portion54 of a tape cassette 53 having a first winding portion 52, a guidemeans including a guide body 55 such as a guide pin and a guide rollerfor guiding the metal evaporated type magnetic tape 51 supplied from thetape cassette 53 into the magnetic head apparatus 60, a second windingportion 56 located at the outside of the tape cassette 53 for windingthe metal evaporated type magnetic tape 51 and rotary drive units (notshown) of the first and second winding portions 52 and 56 fortransporting the metal evaporated type magnetic tape 51 in the outwarddirection and inward direction and vice versa along its longitudinaldirection between the first and second winding portions 52 and 56.

FIG. 2 is a diagram schematically showing an example of a format of themetal evaporated type magnetic tape 51. As shown in FIG. 2, a pluralityof servo bands SB (SB1, SB2, SB3, . . . ) extending along thelongitudinal direction of the metal evaporated type magnetic tape 51 arearrayed with a predetermined interval along the tape width direction,and a plurality of data bands DB (DB1, DB2, DB3, . . . ) are formedacross these servo bands SB.

A large number of data tracks are arranged on these data bands DB inparallel to each other along the longitudinal direction of the metalevaporated type magnetic tape 51.

FIG. 3 is a perspective view schematically showing an arrangement of anexample of the magnetic head apparatus 60 according to the presentinvention. As shown in FIG. 3, this magnetic head apparatus 60 includesa magnetic head main body 61 on which there are mounted a recordingmagnetic head device and a reproducing magnetic head device.

This magnetic head main body 61 is supported on a supporting body 62through a fine following mechanism 80 by which the magnetic head mainbody 61 can be fine moved in the width direction of the metal evaporatedtype magnetic head 51.

This supporting body 62 can be coarsely moved in the width direction ofthe metal evaporated type magnetic tape 51 by a coarse followingmechanism 90.

FIG. 4 is a schematic front view of the magnetic head main body 61. Asshown in FIG. 4, the magnetic head main body 61 comprises an outwardpath recording magnetic head device 1WF and an inward path recordingmagnetic head device 1WR arrayed on the outward path and the inward pathof the outward and inward transport direction for recording data in therecording tracks of the above-mentioned data band DB of the metalevaporated type magnetic tape transported in the outward and inwarddirection along the longitudinal direction of the metal evaporated typemagnetic tape 51 and an outward path reproducing magnetic head device1PF and an inward path reproducing magnetic head device 1PR forreproducing these tracks. This magnetic head main body 61 furtherincludes servo signal reproducing magnetic head devices 1S forreproducing servo signals recorded on the servo bands SB recorded acrossthe data bands DB located above and below the portions in which theoutward path recording magnetic head device 1WF, the inward pathrecording magnetic head device 1WR, the outward path reproducingmagnetic head device 1PF and the inward path reproducing magnetic headdevice 1PRare arranged.

The length of the magnetic head main body 61 is selected to be more thantwice the width of the metal evaporated type magnetic tape 51. When themagnetic head device arrangement portion of the magnetic head main body61 is moved across all of the data bands DB and the servo bands SB ofthe metal evaporated type magnetic tape 51 by the coarse followingmechanism 90, the magnetic head main body 61 is moved across the wholewidth of the metal evaporated type magnetic tape 51 and it can be movedstably and satisfactorily without producing unequal stress on the metalevaporated type magnetic tape 51. The arrangement portion of theabove-mentioned magnetic head devices 1S, 1WF, 1PF, 1WR, 1PR is formedat the central portion of the magnetic head main body 61.

FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 4. Asshown in FIG. 5, the magnetic head main body 61 is formed by bondingfirst and second half portions 61A and 61B, for example.

The first half portion 61A and the second half portion 61B include AlTiCsubstrates 63, for example, on which the above-mentioned magnetic headdevices 1S, 1WF, 1PF, 1WR and 1PR are arranged. As shown in FIG. 5, forexample, the outward path reproducing magnetic head device 1PR and theinward path recording magnetic head device 1WF are laminated on asubstrate 63A of the first half portion 61A, in that order. At the sametime the reproducing magnetic head device 1PR, for example, is formed,the servo signal reproducing magnetic head device 1S is formed. Also,the outward path reproducing magnetic head device 1PF and the inwardpath recording magnetic head device 1WR are laminated on a substrate 63Bof the second half portion 61B, in that order. At the same time thereproducing magnetic head device 1PF, for example, is formed, the servosignal reproducing magnetic head device 1S is formed.

The outward path and inward path recording magnetic head devices 1WF and1WR can be composed of electromagnetic induction type magnetic headsformed of thin film devices, and the outward path and inward pathreproducing magnetic head devices 1PF and 1PR can be composed ofmagnetoresistive devices (MR devices), for example.

The outward path reproducing magnetic head device 1PR and the inwardpath reproducing magnetic head device 1PF can be composed of amagnetoresistive type magnetic head element including a magnetoresistive(MR) device disposed between a lower magnetic layer 64 and an uppermagnetic layer 65 formed of a magnetic layer made of a suitable materialsuch as permalloy and sendust formed on the substrates 63, for example.The servo signal reproducing magnetic head device 1S can be composed ofthe magnetoresistive type magnetic head device at the same time theoutward path reproducing magnetic head device 1PR and the inward pathreproducing magnetic head device 1PF are formed.

Then, the outward path recording magnetic head device 1WF and the inwardpath recording magnetic head device 1WR, each of which is formed of athin film magnetic head, are formed on the inward path reproducingmagnetic head device 1PR and the outward path reproducing magnetic headdevice 1PF.

These recording magnetic head devices 1WF and 1WR have a first magneticbody 66 and a second magnetic body 67 laminated with each other throughnonmagnetic layers so as to serve magnetic cores to form operationmagnetic gaps GF and GR between the front portions thereof.

Also, a thin film coil 68 comprising, for example, a head winding isdisposed between the first and second magnetic bodies 66 and 67.

In this case, the first magnetic body 66 can serve both as the firstmagnetic body 66 and the upper magnetic layer 65.

Then, in the outward path recording magnetic head device 1WF and theinward path recording magnetic head device 1WR, at least the secondmagnetic body 67 is formed of a thin film magnetic body.

Protecting films 69 are deposited on the respective recording magnetichead devices 1WF and 1WR by sputtering alumina, for example.

Laminated head portions composed of a plurality of reproducing magnetichead device 1PF, 1PR and recording magnetic head devices 1WF, 1WRarranged in the direction perpendicular to the sheet of the drawing ofFIG. 5 are arranged on the first and second half portions 61A and 61Balong the track width direction of the metal evaporated type magnetictape 51.

The first and second half portions 61A and 61B are bonded by theirsubstrates 63 and thereby formed as one body to construct the magnetichead device main body 61.

In this state, as shown in FIG. 4, a plurality of outward path recordingmagnetic head devices 1WF and a plurality of inward path recordingmagnetic head elements 1WR are arranged on two parallel straight lineswith a predetermined spacing.

These outward path recording magnetic head devices 1WF and these inwardpath recording magnetic head devices 1WR are arranged on the same datatrack, for example, in parallel to each other. The inward pathreproducing magnetic head devices 1PR is parallelly located on the sideadjacent to the outward path recording magnetic head device 1WF betweenthe outward path recording magnetic head device 1WF and the inward pathrecording magnetic head device 1WR which are located in parallel to eachother. The outward path reproducing magnetic head device 1PF isparallelly located on the side adjacent to the inward path recordingmagnetic head device 1WR between the outward path recording magnetichead device 1WF and the inward path recording magnetic head device 1WRwhich are located in parallel to each other.

In this arrangement, a front surface 61F of the magnetic head main body61 serves as the transport surface of the metal evaporated type magnetictape 51, that is, the surface along which the metal evaporated typemagnetic tape 51 is transported in slidable contact with the magnetichead main body 61 or in an opposing fashion to the magnetic head mainbody 61.

FIG. 6 is a schematic diagram showing a flat surface pattern of therecording magnetic heads of the magnetic head apparatus according to thepresent invention. In the above-mentioned arrangement, as shown in FIG.6, a width of the front portion comprising the operation magnetic gap GFor GR of the recording magnetic head device 1WF or 1WR formed of thethin film magnetic head is selected to be a width W1 sufficiently largerthan the track width of the operation magnetic gap GF or GR with respectto the first magnetic body 67 of the lower layer and it is selected tobe a width W2 corresponding to the target track width of the operationmagnetic gap GF or GR with respect to the second magnetic body 67 of theupper layer formed of at least the thin film magnetic layer. The trackwidth of the operation magnetic gap GF or GR is determined by the widthW2 of the front portion of the second magnetic body 67.

As described above, the operation magnetic gaps GF and GR have anasymmetric structure narrowed with the width W2 of the front portion ofthe second magnetic body 67.

Then, as mentioned above, the magnetic head main body 61 is attached tothe supporting body 62 through the fine following mechanism 80.

As shown in FIG. 3, this fine following mechanism 80 comprises a pair ofbimorph elements 81, one ends of which are fixed to the supporting body62 with a predetermined spacing, for example (only one bimorph element81 is shown in FIG. 3).

As shown in FIG. 3, the magnetic head main body 61 is bonded at itsrespective ends of the track width direction to the free ends of thesebimorph elements 81 through an attachment member 82.

On the other hand, as shown in FIG. 3, the coarse following mechanism 90includes a tapped hole 91 bored on the supporting body 62 along thetrack width direction and a rotary screw shaft 93 reciprocally rotatedby a rotary driving portion 92 formed of a suitable means such as astepping motor. The supporting body 62 can be moved in the track widthdirection, that is, it can be rotatably moved in the width direction ofthe metal evaporated type magnetic tape 51. Also, the supporting body 62can be moved in the track width direction as the rotary shaft 93 isrotated by the rotary driving portion 92.

In this manner, the supporting body 62 can be fine moved in the widthdirection of the metal evaporated type magnetic tape 51 by the coarsefollowing mechanism 90, whereby the magnetic head device arrangementportion of the magnetic head main body 61 can be brought to the positionof the target data band DB and the position of the servo band SB at bothsides of the data band DB of the metal evaporated type magnetic tape 51.Thus, the recording magnetic head devices 1WF and 1WR can be coarselyadjusted so as to reach the positions of the selected data tracks whenthe metal evaporated type magnetic tape 51 is transported in the outwardand inward direction and vice versa.

Tracking errors are detected by the servo signal read out from the trackof the metal evaporated type magnetic tape 51 by the servo signalreproducing magnetic head device 1S, whereby the magnetic head main body61 is fine adjusted with application of a control signal voltage to thebimorph elements 81 of the fine following mechanism 80 and therespective recording magnetic head devices 1WF and 1WR and reproducingmagnetic head devices 1PF and 1PR can be accurately set to the centersof the data tracks upon tracking adjustment.

According to this magnetic head apparatus, when the metal evaporatedtype magnetic tape 51 is transported in the outward path during it istransported in the outward and inward direction and vice versa, data ismagnetically recorded on the selected track by the outward pathrecording magnetic head device 1WR of the magnetic head main body 61.Subsequently, the thus recorded data is reproduced for monitoring by theoutward path reproducing magnetic head device 1PF on the selected track.

Then, when the metal evaporated type magnetic tape 51 is transported inthe inward path, as mentioned above, the magnetic head main body 61 ismoved in the track width direction (tape width direction) and data ismagnetically recorded on other selected tracks by the inward pathrecording magnetic head device 1WR. Subsequently, the thus recorded datais reproduced for monitoring by the inward path reproducing magnetichead devices 1PR on other selected tracks.

According to the present invention, in the magnetic head apparatushaving the above-mentioned arrangement, for example, the side of thesecond magnetic body 67 with the narrow front portion comprising theoperation magnetic gaps GF and GR having asymmetric structurescomprising the recording magnetic heads 1WF and 1WR is located on theleading side, that is, the entrance side in which the metal evaporatedtype magnetic tape 51 is entered into the magnetic head device.

Next, characteristics of the recording magnetic head apparatus havingthe above-mentioned arrangement according to the present invention willbe described below.

In this case, a mechanism in which remanent magnetization is generatedwhen recording magnetic fields produced from the magnetic gaps with theasymmetric structures in which the front portions of the first andsecond magnetic bodies 66 and 67 are different in width act on the metalevaporated type magnetic tape having rhombic magnetic anisotropy isextremely complex. Therefore, the characteristics of the recordingmagnetic head apparatus according to the present invention will bedescribed with reference to measured results of recording andreproducing characteristics relative to the metal evaporated typemagnetic tape with the rhombic magnetic anisotropy, more specifically,frequency characteristics, input and output characteristics, etc.

A single layer metal evaporated type magnetic tape having a 55 nm-thickmagnetic layer should be used as a magnetic tape and a thin filmmagnetic head device with an asymmetric structure having a track widthof 2.75 μm and a gap length of 0.30 μm should be used as a recordingmagnetic head device and an MR (magnetoresistive) head having a trackwidth of 7 μm and a gap length of 0.23 μm should be used as areproducing magnetic head device until otherwise specified. Recordingand reproducing characteristics of the recording magnetic head deviceand the reproducing magnetic head device were measured by a so-calleddrum tester. More specifically, the above-mentioned single layer metalevaporated type magnetic tape was wound around a rotary drum, therotation directions of the recording magnetic head device and thereproducing magnetic head device were selected and the slidingoperations of the respective operation magnetic gaps of theabove-mentioned recording magnetic head device and reproducing magnetichead device were measured.

Recording and reproducing characteristics of the recording magnetic headapparatus were measured in consideration of the relationship between theoutward path magnetic head device 1WF, the inward path magnetic headdevice 1WR and the metal evaporated type magnetic tape 51 schematicallyshown in FIGS. 7A and 7B.

In this case, the running direction of the metal evaporated typemagnetic tape 51 is assumed as follows. That is, the transport directionin which the magnetic head devices 1WF and 1WR are transported relativeto the direction (hereinafter referred to as a “forward direction”)extending along the inclination of columns 100 of the metal evaporatedtype magnetic tape 51 is assumed to be an outward path transportdirection FWD. Also, the transport direction in which the magnetic headdevices 1WF and 1WR are transported relative to the opposite direction(hereinafter referred to as a “reverse direction”) extending along theinclination of columns 100 of the metal evaporated type magnetic tape 51is assumed to be an inward path transport direction REV.

FIG. 7A shows the layout corresponding to the above-mentionedarrangement of the present invention. More specifically, the secondmagnetic bodies 67 with narrow front portions, of the outward pathrecording magnetic head device 1WF and the inward path magnetic headdevice 1WR, for determining the track widths of their magnetic gaps GFand GR are both located at the outside, that is, they are located at theleading sides with respect to the outward path and the inward path(hereinafter this layout will be referred to as a “type A”).

On the other hand, conversely to FIG. 7A, FIG. 7B shows the case inwhich the second magnetic bodies 67 with the narrow front portions ofthe outward path recording magnetic head device 1WF and the inward pathmagnetic head device 1WR are both located on the inside. In FIG. 7B,elements and parts identical to those of FIG. 7A are denoted byidentical reference numerals and therefore need not be described. Morespecifically, the outward path and inward path recording magnetic headdevices 1WF and 1WR are located on the trailing side with respect to thetransport directions of the outward path and the inward path of themetal evaporated type magnetic tape 51 (hereinafter this layout will bereferred to as a “type B”).

In FIG. 7B, if the inward path recording magnetic head device 1WR isused as the outward path recording magnetic head device and the outwardpath recording magnetic head device 1WF is used as the inward pathrecording magnetic head device, then with respect to the outward pathand the inward path, the second magnetic bodies 67 are located on theleading side.

However, in actual practice, when data is recorded on the metalevaporated type magnetic tape 51 by the recording magnetic head device1WR, for example, the reproducing magnetic head devicet for monitoringrecorded data should be located on the rear stage side with respect tothe transport of the tape. To this end, a thin film magnetic head devicecomprising the recording magnetic head device should be formed on thesame substrate 63 on which the above-mentioned recording magnetic headdevice 1WR is formed and a magnetoresistive type magnetic head devicecomprising the reproducing magnetic head device should be formed on thethin film magnetic head device.

However, when the recording magnetic head device and the reproducingmagnetic head device are laminated on the common substrate, both of therecording magnetic head device and the reproducing magnetic head deviceare located too close to each other, which is not practical in actualuse.

Therefore, according to the arrangement of the present invention, thetype A schematically shown in FIG. 7A becomes a representing example.

FIGS. 8 to 13 are diagrams showing characteristic curves obtained whencharacteristics of reproduced outputs of the magnetic heads are measuredby the aforementioned drum tester.

In this case, under the conditions in which the magnetic tape having theabove-mentioned rhombic magnetic anisotropy is wrapped around the rotarydrum, the magnetic head device is brought in slidable contact with thismagnetic tape and the rotation direction of the rotary drum and thelayout of the magnetic head devices, etc. are selected, characteristicsof the type A recording magnetic head and the type B recording magnetichead were measured.

FIG. 8 is a diagram showing characteristic curves obtained whenfrequency characteristics of the type A recording magnetic head and thetype B recording magnetic head, that is, changes of outputs relative tofrequencies were measured. In this case, a recording current Iw wasselected to be an optimum recording current value ORC (Optimum RecordingCurrent) at a recording frequency of 24 MHz.

FIG. 9 is a diagram showing characteristic curves obtained when inputand output characteristics, that is, recording current dependences ofreproduced outputs from the type A recording magnetic head and the typeB recording magnetic head, similarly. That is, the recording current I2is exhibited as [mA_(0-p)] (zero-to-peak current value).

In FIGS. 8 and 9, solid triangles AFWD and open triangles AREV showcharacteristics plotted when data was recorded on and reproduced fromthe metal evaporated type magnetic tape 51 running in the FWD directionby the outward path recording magnetic head device 1WF in the type Amagnetic head and characteristics plotted when data was recorded on andreproduced from the metal evaporated type magnetic tape 51 running inthe REV direction by the inward path recording magnetic head 1WR.

Also, solid squares BFWD and open squares BREV show characteristicsplotted when data is recorded on and reproduced from the metalevaporated type magnetic tape 51 running in the FWD direction by theoutward path magnetic head device 1WF in the type B magnetic head andcharacteristics plotted when data is recorded on and reproduced from themetal evaporated type magnetic tape 51 running in the REV direction bythe inward path recording magnetic head device 1WR in the type Bmagnetic head.

A study of FIG. 8 reveals that the frequency characteristic of the typeA magnetic head is approximately 2 dB and which is excellent as comparedwith that of the type B magnetic head and that the reproduced outputthereof is increased 2 dB in the forward direction and is also increased5 dB in the reverse direction. That is, when the metal evaporated typemagnetic tape having the rhombic magnetic anisotropy is in use, thefrequency characteristic can be improved, particularly, in the reversedirection.

A study of FIG. 9 reveals that the optimum recording current of the typeA magnetic head is substantially equal to that of the type B magnetichead during the metal evaporated type magnetic tape is transported inthe forward direction and that the above-mentioned optimum recordingcurrent is increased 10% during the metal evaporated type magnetic tapeis transported in the reverse direction.

As described above, according to the arrangement of the type A magnetichead of the present invention, frequency characteristics and recordingand reproducing characteristics can be improved even in the inward pathtransport which becomes the reverse direction, for example.

Further, when the present invention is applied to a so-calledmulti-channel linear system in which a large number of magnetic headdevices are arrayed in the track width direction as described above, thetype A magnetic head can decrease a difference between electromagnetictransduction characteristics obtained when the metal evaporated typemagnetic tape is transported in the forward direction and the reversedirection.

Therefore, signal processing in the above-mentioned recording andreproducing channels can be executed by a circuit having similarcharacteristics in the forward and reverse directions and hence a simplemagnetic recording system can be constructed.

Also, it is possible to realize an inexpensive system.

Further, according to the arrangement of the present invention,recording and reproducing characteristics deteriorated upon off-trackcan be improved.

FIGS. 10, 11, 12 and 13 are diagrams showing characteristic curvesobtained when frequency characteristics and recording currentdependences of reproduced outputs in the case in which the narrow thinfilm magnetic core (second magnetic body 67) comprising theabove-mentioned operation magnetic gap is located at the leading sidewith respect to the metal evaporated type magnetic tape 51 like the typeA magnetic head with the arrangement according to the present inventionand in the case in which the narrow thin film magnetic core (secondmagnetic body 67) comprising the above-mentioned operation magnetic gapis located at the trailing side with respect to the metal evaporatedtype magnetic tape 51 like the type B magnetic head with the arrangementaccording to the present invention under the conditions in which arelationship between a recording track width Tww and a reproducing trackwidth Twr is selected to be Tww<Twr, for example, Tww=2.8μ and Twr=7μand in which the above-mentioned relationship is selected to be Tww>Twr,for example, Tww=13 μm and Twr=7 μm, respectively. In FIGS. 10 and 11,the recording current Im is selected to be the optimum current value ata frequency of 24 MHz. Further, in FIGS. 12 and 13, the recordingcurrent Im is exhibited as [mA_(p-p)] (peak-to-peak current value).

In FIGS. 10, 11, 12 and 13, solid triangles AFWD and open triangles AREVshow characteristics plotted when data is recorded on and reproducedfrom the metal evaporated type magnetic tape 51 running in the FWDdirection by the outward path recording magnetic head device 1WF in thetype A magnetic head and when data is recorded on and reproduced fromthe metal evaporated type magnetic tape 51 running in the REV directionby the inward path recording magnetic head 1WR in the type A magnetichead.

Also, in FIGS. 10, 11, 12 and 13, solid squares BFWD and open squaresBREV show characteristic plotted when data is recorded on and reproducedfrom the metal evaporated type magnetic tape 51 running in the FWDdirection by the outward path recording magnetic head device 1WF in thetype B magnetic head and when data is recorded on and reproduced fromthe metal evaporated type magnetic tape 51 running in the REV directionby the inward path recording magnetic head 1WR in the type B magnetichead.

As is clear from the comparison with FIGS. 10 and 11 and the comparisonwith FIGS. 12 and 13, when the reproducing track width is made smallerthan the recording track width (Tww>Twr), the influence of the magneticfield distortions produced in the track width direction by the narrowthin film magnetic core (second magnetic body) having the operationmagnetic gap with the asymmetric structure can be improved by thereduced reproduced track width.

Then, recording patterns obtained by the above-mentioned type A magnetichead and type B magnetic head were observed by an MFM (magnetic forcemicroscope). FIGS. 14 and 15 are pattern diagrams schematically showingthe observed patterns. In this case, the recording track width of therecording magnetic head is selected to be 5.2 μm.

As described above, when the narrow thin film magnetic core (secondmagnetic body 67) of the magnetic gap is located at the leading side andthe wide magnetic core (first magnetic layer 66) is located at thetrailing side, as shown in FIG. 14, the recording tracks are formed aspatterns without distortion up to the edge portion of the track widthdirection. Conversely, when the narrow thin film magnetic core (secondmagnetic body 67) of the magnetic gap is located at the trailing side,the distortion of this edge portion exerts an influence upon therecording tracks and hence the edge portions of the width direction ofthe recording tracks are bent as shown by broken lines b in FIG. 15.

From the above descriptions, according to the type A magnetic head, therecording tracks are correctly formed over the whole area of the trackwidth. However, according to the type B head, the bent recordingpatterns exist at both sides of the track width and hence it can beconsidered that output is decreased the amount corresponding to theamount decreased by the bent recording track patterns. This is caused bymagnetization left when the metal evaporated type magnetic tape havingeasy axis of magnetization in the slanting direction is applied withcomplex recording magnetic fields.

From the above-mentioned results, it is to be understood that the thinfilm magnetic recording head with the magnetic gap with the asymmetricstructure has excellent frequency characteristics and outputs dependingupon the running direction thereof. Thus, when the recording head is setin the direction of the type A magnetic head like the present invention,it is possible to construct a magnetic recording system with excellentfrequency characteristics and outputs.

Also, as is clear from the above descriptions, a difference between thetransport directions can be decreased upon off-track and it is possibleto construct a system which is strong against the off-track.

While the present invention is applied to the magnetic head with theasymmetric structure mainly in the thin film magnetic head as set forthabove, the present invention is not limited thereto and can also beapplied to the case in which the metal evaporated type magnetic tape isused in various kinds of recording magnetic heads with operationmagnetic gaps having asymmetric structures. Thus, it is needless to saythat the present invention can be applied to the magnetic head apparatusand the drive apparatus including the magnetic head apparatus accordingto the above-mentioned embodiments.

As described above, in the magnetic head apparatus and the driveapparatus according to the present invention, the recording magnetichead device capable of at least recording data includes one of the firstand second magnetic bodies comprising the operation magnetic gap, thatis, the second magnetic body having the asymmetric structure with thenarrow width. In this manner, since only one magnetic body forms theoperation magnetic gap structure with the asymmetric structure todetermine the track width, the track width of the operation magnetic gapcan be set to be narrow and accurate as mentioned before. Further, whenthe second magnetic body is composed of the thin film magnetic body, thenarrow track width can be determined with higher accuracy.

Further, according to the present invention, in the recording magnetichead device with the operation magnetic gap having this asymmetricstructure, the second magnetic body with the narrow width is located onthe leading side with respect to the direction in which the recordingmagnetic head device is transported relative to the metal evaporatedtype magnetic tape, that is, the second magnetic body is located on theentrance side in which the metal evaporated type magnetic head entersinto the recording magnetic head device. According to this arrangement,as is clear from the descriptions which will be made later on, even inthe metal evaporated type magnetic tape having the rhombic anisotropy,degree between the electromagnetic transduction characteristics becomedifferent due to the transport direction of the metal evaporated typemagnetic tape can be decreased. In addition, it is possible to improvedeteriorations of the reproduced signal deteriorated when thereproducing magnetic head is shifted from the center of the recordingtrack, that is, off-track occurs.

That is, according to the present invention, the high density recordingcan be realized by the magnetic gap with the asymmetric structure. Inthis case, it can be considered that the aforementioned problemsencountered with the related art can be solved by alleviating bothinfluence of distortion of the recording magnetic field produced at theedge portion of the track width direction by the second magnetic bodywith the narrow width comprising the operation magnetic gap andinfluence of polarity of evaporated particles produced by rhombicvapor-deposition.

Having described preferred embodiments of the invention with referenceto the accompanying drawings, it is to be understood that the presentinvention is not limited to those precise embodiments and that variouschanges and modifications could be effected therein by one skilled inthe art without departing from the spirit or scope of the invention asdefined in the appended claims.

1. A magnetic head apparatus comprising: a magnetic head main bodyincluding an outward path recording magnetic head device and an inwardpath recording magnetic head device for carrying out at least magneticrecording to form recording tracks on an outward path and an inward pathof the outward and inward transport of a metal evaporated type magnetictape along the longitudinal direction of said metal evaporated typemagnetic tape while said metal evaporated magnetic tape is transportedin the outward and inward direction and vice versa along thelongitudinal direction, wherein said recording magnetic head device iscomposed of opposing first and second magnetic bodies, said opposingfirst and second magnetic bodies having an operation magnetic gap formedbetween their front portions, said operation magnetic gap has anasymmetric structure in which a width of said front portion of saidsecond magnetic body is selected to be narrower than that of said frontportion of said first magnetic body, a track width of said operationmagnetic gap being determined by a width of the front portion of saidmagnetic body, and said outward path recording magnetic head device andsaid inward path recording magnetic head device are located in such amanner that said second magnetic body having said front portion with thenarrow width is located on the leading side with respect to thedirection of the outward path and the inward path of said metalevaporated type magnetic tape.
 2. A magnetic head apparatus according toclaim 1, wherein said outward path recording magnetic head device andsaid inward path recording magnetic head device have said secondmagnetic bodies made of thin film magnetic material to form saidoperation magnetic gaps at their narrow front portions.
 3. A magnetichead apparatus according to claim 1, wherein said magnetic head mainbody has a plurality of said outward path recording magnetic headdevices and a plurality of said inward path recording magnetic headdevices arrayed on parallel different straight lines with apredetermined spacing, said inward path reproducing magnetic head isformed on the side adjacent to said outward path recording magnetic headdevice in the portion where said outward path recording magnetic headdevice and said inward path recording magnetic head device are arrayed,said outward path reproducing magnetic head device is formed on the sideadjacent to said inward path recording magnetic head device, saidmagnetic head main body is moved in the width direction of said metalevaporated type magnetic tape with respect to said outward path and saidinward path, with respect to said outward path, said outward pathrecording magnetic head device magnetically records data on a selectedtrack and said outward path reproducing magnetic head on said selectedtrack reproduces recorded data, and with respect to said inward path,said inward path recording magnetic head device magnetically recordsdata on other selected track and said inward path reproducing magnetichead device on said other selected track magnetically reproducesrecorded data.
 4. A drive apparatus including a transport drive unit fortransporting a metal evaporated magnetic tape in the outward and inwarddirection and vice versa and a magnetic head apparatus includingmagnetic head devices for recording and reproducing said metalevaporated magnetic tape, comprising a magnetic head apparatus, saidmagnetic head apparatus comprising a magnetic head main body includingan outward path recording magnetic head device and an inward pathrecording magnetic head device for carrying out at least magneticrecording to form recording tracks on an outward path and an inward pathof the outward and inward transport of a metal evaporated type magnetictape along the longitudinal direction of said metal evaporated typemagnetic tape while said metal evaporated magnetic tape is transportedin the outward and inward direction and vice versa along thelongitudinal direction, wherein said recording magnetic head device iscomposed of opposing first and second magnetic bodies, said opposingfirst and second magnetic bodies having an operation magnetic gap formedbetween their front portions, said operation magnetic gap has anasymmetric structure in which a width of said front portion of saidsecond magnetic body is selected to be narrower than that of said frontportion of said first magnetic body, a track width of said operationmagnetic gap being determined by a width of the front portion of saidmagnetic body, and said outward path recording magnetic head device andsaid inward path recording magnetic head device are located in such amanner that said second magnetic body having said front portion with thenarrow width is located on the leading side with respect to thedirection of the outward path and the inward path of said metalevaporated type magnetic tape.
 5. A drive apparatus including a magnetichead apparatus according to claim 4, wherein said outward path recordingmagnetic head device and said inward path recording magnetic head devicehave said second magnetic bodies made of thin film magnetic material toform said operation magnetic gaps at their narrow front portions.
 6. Adrive apparatus including a magnetic head apparatus according to claim4, wherein said magnetic head main body has a plurality of said outwardpath recording magnetic head devices and a plurality of said inward pathrecording magnetic head devices arrayed on parallel different straightlines with a predetermined spacing, said inward path reproducingmagnetic head is formed on the side adjacent to said outward pathrecording magnetic head device in the portion where said outward pathrecording magnetic head device and said inward path recording magnetichead device are arrayed, said outward path reproducing magnetic headdevice is formed on the side adjacent to said inward path recordingmagnetic head device, said magnetic head main body is moved in the widthdirection of said metal evaporated type magnetic tape with respect tosaid outward path and said inward path, with respect to said outwardpath, said outward path recording magnetic head device magneticallyrecords data on a selected track and said outward path reproducingmagnetic head on said selected track reproduces recorded data, and withrespect to said inward path, said inward path recording magnetic headdevice magnetically records data on other selected track and said inwardpath reproducing magnetic head device on said other selected trackmagnetically reproduces recorded data.